Date: Fri, 7 Oct 2011 14:54:37 -0400 (EDT) From: Benjamin Kaduk <kaduk@MIT.EDU> To: Warren Block <wblock@wonkity.com> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org, Arnaud Lacombe <lacombar@gmail.com> Subject: Re: aliasing (or renaming) kern.geom.debugflags Message-ID: <alpine.GSO.1.10.1110071453420.882@multics.mit.edu> In-Reply-To: <alpine.BSF.2.00.1110071236270.2450@wonkity.com> References: <80750.1318010551@critter.freebsd.dk> <alpine.BSF.2.00.1110071210040.2450@wonkity.com> <CACqU3MXtCF2u7SLYs8Fg3oqyzpS=GTVMTXx_9E6zYhfVEpRNow@mail.gmail.com> <alpine.BSF.2.00.1110071236270.2450@wonkity.com>
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On Fri, 7 Oct 2011, Warren Block wrote: > On Fri, 7 Oct 2011, Arnaud Lacombe wrote: > >> Hi, >> >> On Fri, Oct 7, 2011 at 2:13 PM, Warren Block <wblock@wonkity.com> wrote: >>> On Fri, 7 Oct 2011, Poul-Henning Kamp wrote: >>> >>>> In message <alpine.GSO.1.10.1110071341430.882@multics.mit.edu>, Benjamin >>>> Kaduk >>>> writes: >>>> >>>>> Now, an ordinary user who is >>>>> doing this for the first time might ask, "why do I need to do something >>>>> with 'debugflags' in order to make a USB stick? >>>> >>>> Which is the exactly right question to ask. >>>> >>>> The procedure documented is clearly flawed. >>> >>> Probably a misunderstanding on my part, since I suggested it to Glen. >>> Can't >>> recall the circumstances exactly. >>> >>> The next question would be: what is the correct procedure? >>> >> I'd guess the procedure involves shooting your feet: >> >> from `sys/geom/geom_subr.c': >> >> /* If foot-shooting is enabled, any open on rank#1 is OK */ >> if ((g_debugflags & 16) && pp->geom->rank == 1) >> ; > > Well, yes. The goal is to unprotect the device, regardless of what may > already be on it. Then the user can overwrite it with the memory stick > image. > > The current documentation is > > sysctl kern.geom.debugflags=16 > dd if=memstick.img of=/dev/whatever0 bs=64k I presume that Poul-Henning was not claiming that the documentation did not match the functional procedure, but rather that the procedure needed to achieve the goal (of a functional USB stick) is flawed. (Even if it is correctly documented.) -Ben
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